Underpants-type disposable diaper

ABSTRACT

A cover nonwoven fabric covers a back surface of an inner member from between a front side outer member and the inner member to between a back side outer member and the inner member. In this cover nonwoven fabric, a large number of holes are provided at intervals. The holes penetrate the front surface and back surface from between the front side outer member and the inner member to between the back side outer member and the inner member. The front side outer member and the back side outer member have, at least at portions overlapping with the cover nonwoven fabric and not having any elastic member, a total luminous transmittance of 50% or more.

TECHNICAL FIELD

The present invention relates to an underpants-type disposable diaper.

BACKGROUND ART

As for underpants-type disposable diapers, an outer member one unit-typeand an outer member separated-type are known. An inner memberincorporating an absorber is attached to an outer member continuouslyextending throughout the whole front-back direction in the outer memberone unit-type. In the outer member separated-type, a front side outermember disposed in a front body and a back side outer member disposed ina back body are separately provided, and the front side outer member andthe back side outer member are spaced apart in the front-back directionat the middle in the front-back direction. The inner member includingthe absorber extends in the front-back direction from the front sideouter member to the back side outer member and is joined to the frontside outer member and to the back side outer member. As an outer member,it is common to use a nonwoven fabric to ensure air permeability with anouter surface like a cloth. Particularly, in the outer memberseparated-type underpants-type disposable diaper, since an inner memberis exposed between a front side outer member and a back side outermember, it is known to provide a cover nonwoven fabric covering a backsurface of the inner member such that a liquid impervious sheet is notexposed on the back surface of the inner member.

Recently, to further improve air permeability in disposable diapers, ithas been proposed to use a perforated nonwoven fabric in which a largenumber of holes are formed at intervals as a nonwoven fabric used for anouter member (refer to Patent Literature 1). Such a perforated nonwovenfabric has an effect of adding functional beauty in air permeabilityimprovement, such that it is extremely important to visually recognizethe presence of holes (visual effect). In this point, since PatentLiterature 1 discloses an outer member one unit-type, when a perforatednonwoven fabric is used for a nonwoven fabric of an outer member, almostall holes can be visually recognized.

However, when a perforated nonwoven fabric is used for a cover nonwovenfabric to improve air permeability of a crotch portion of the outermember separated-type underpants-type disposable diaper, the frontportion and the back portion of the cover nonwoven fabric are hidden bya front side outer member and a back side outer member. Therefore, evenif a perforated nonwoven fabric is provided in this cover nonwovenfabric, since a user cannot visually recognize the presence of thishole, it is likely to be misunderstood that theair-permeability-improving function is provided only in the portionbetween the front side outer member and the back side outer member. Inthis case, the visual effect is not sufficiently exhibited, and there isa problem that the air-permeability-improving function which is aproduct feature is not correctly known to users.

CITATION LIST Patent Literature

Patent Literature 1: JP 2015-128573 A

SUMMARY OF INVENTION Technical Problem

In view of the above, a main object of the present invention is toimprove the visual effect of holes when a perforated nonwoven fabric isused for a cover nonwoven fabric in an outer member separated-typeunderpants-type disposable diaper.

Solution to Problem

The representative aspects of the present invention that have solved theabove problems will be described below.

First Aspect

An underpants-type disposable diaper, in which a front side outer memberdisposed in a front body and a back side outer member disposed in a backbody are separately provided, the front side outer member and the backside outer member are spaced apart in the front-back direction at themiddle in the front-back direction,

an inner member having a liquid pervious top sheet, a liquid impervioussheet, and an absorber interposed therebetween extends in the front-backdirection from the front side outer member to the back side outermember, the inner member is joined to each of the front side outermember and the back side outer member,

a cover nonwoven fabric covering a back surface of the inner member isprovided from between the front side outer member and the inner memberto between the back side outer member and the inner member,

both sides of the front side outer member and both sides of the backside outer member are joined to each other, a waist opening and a pairof right and left leg openings are included, and

elastic members are incorporated in the front side outer member and theback side outer member,

wherein the cover nonwoven fabric is provided with a plurality of holespenetrating a front surface and a back surface of the cover nonwovenfabric from between the front side outer member and the inner member tobetween the back side outer member and the inner member at intervals,and

the front side outer member and the back side outer member have, atleast at portions overlapping with the cover nonwoven fabric and nothaving any elastic member, a total luminous transmittance of 50% ormore.

Function and Effect

As described above, the front side outer member and the back side outermember have, at least at portions overlapping with the cover nonwovenfabric and not having any elastic member, a total luminous transmittanceof 50% or more. Therefore, even in portions of the cover nonwovenfabric, which are hidden by the front side outer member and the backside outer member, the holes of the perforated nonwoven fabric aretransparent and can be visually recognized sufficiently, and a user canrecognize that in the cover nonwoven fabric, not only a portion betweenthe front side outer member and the back side outer member but alsofront and back sides of this portion have air-permeability-improvingfunction. Therefore, the visual effect of the holes is sufficientlyexhibited, and the air-permeability-improving function which is aproduct feature is properly known to a user.

Second Aspect

The underpants-type disposable diaper according to the first aspect,comprising inner decorative printing, which is visible on outer surfacesof the front side outer member and the back side outer member, on theliquid impervious sheet at least in a region thereof, which overlaps thefront side outer member and the back side outer member,

wherein the inner decorative printing overlaps with the holes at leastin a part of the cover nonwoven fabric.

Function and Effect

In the underpants-type disposable diaper, decorative printing (innerdecorative printing) such as characters and patterns may be provided onthe liquid impervious sheet so as to be visible on a product outersurface. Through the using of such decorative printing, when the innerdecorative printing and the holes at least in a part of the covernonwoven fabric are overlapped, the holes of the perforated nonwovenfabric emerge on a background of the inner decorative printing, and itis preferable since the holes are likely to be seen through the outersurface.

Third Aspect

The underpants-type disposable diaper according to the second aspect,wherein at least either of a region where the front side outer memberand the cover nonwoven fabric overlap with each other and a region wherethe back side outer member and the cover nonwoven fabric overlap witheach other includes, on an outer side of the cover nonwoven fabric, aportion provided with an outer decorative sheet having outer decorativeprinting and a portion not having the outer decorative sheet.

Function and Effect

Since the inner decorative printing described before is covered with theperforated nonwoven fabric, the appearance as a decoration may bedeteriorated. Therefore, for the decoration emphasizing the appearance,it is desirable to separately provide the outer decorative sheet asdescribed above and to add the outer decorative printing there.

Fourth Aspect

The underpants-type disposable diaper according to the third aspect,wherein the inner decorative printing is a continuous decorativeprinting comprising a plurality of elements regularly repeating in thefront-back direction and the width direction, and the outer decorativeprinting is an intermittent decorative printing arranged only in one orboth of front and back sides of a product.

Function and Effect

Decorative printing in an underpants-type disposable diaper is notlimited to a continuous decorative printing consisting of a large numberof elements such as letters and pictures which are regularly repeated inthe front-back direction and the width direction and may be anintermittent decorative printing arranged only in one or both of thefront and back sides of the product such as product logos, pictures ofcharacters, and the like. The continuous decorative printing is arepetition of a large number of elements, and there is almost noinfluence on appearance even as a background of the perforated nonwovenfabric. However, when the intermittent decorative printing is coveredwith the perforated nonwoven fabric, there is a difference in appearancebetween portions having the holes and the other portions, and theintermittent decorative printing is partly hidden due to high concealingproperty of edge portions of the holes. Consequently, the deteriorationof appearance becomes remarkable. Therefore, it is desirable todistinguish a member having the inner decorative printing and a memberhaving the outer decorative printing, and, as described above, to applythe continuous decorative printing to the inner decorative printing andapply the intermittent decorative printing to the outer decorativeprinting.

Fifth Aspect

The underpants-type disposable diaper according to any one of the firstto fourth aspects, wherein at least either of the front side outermember and the back side outer member is joined to the inner member, atregions overlapping with both end portions in the width direction of theinner member, and is not joined or is intermittently and peelably joinedto the inner member, at a part on a crotch side or a whole part in thefront-back direction of a region between the regions overlapping withthe both end portions in the width direction of the inner member.

Function and Effect

In this manner, since the portion joining the inner member and at leastone of the front side outer member and the back side outer member is notjoined or is intermittently and peelably joined, at the part on thecrotch side or at the whole part throughout in the front-back direction,gaps formed between the inner member and at least one of the front sideouter member and the back side outer member communicate with the crotchside and improve air permeability. In addition, since the cover nonwovenfabric (perforated nonwoven fabric) hidden by at least one of the frontside outer member and the back side outer member can be directly seen bypulling up this part, the higher visual effect of the holes can beobtained.

Sixth Aspect

The underpants-type disposable diaper according to any one of the firstto fifth aspects, comprising side gathers extending from both sides ofthe inner member so as to be in contact with the legs of a wearer andeach of the side gathers having a base end on a side portion on a backsurface side of the liquid impervious sheet in the inner member, and agather nonwoven fabric forming an outer surface at least from the baseend to a tip end,

wherein the cover nonwoven fabric extends at least from between a baseportion of one of the side gathers and the liquid impervious sheet tobetween a base portion of the other side gather and the liquid imperioussheet, and

the gather nonwoven fabric has a total luminous transmittance of 60 to90%.

Function and Effect

When the side edges of the cover nonwoven fabric are covered with thegather nonwoven fabrics of the side gathers as described before, theside edges of the cover nonwoven fabric are unlikely to contact the legsof the wearer, and the side edges of the gather nonwoven fabric alsoface toward the center in the width direction and are unlikely tocontact the legs of the wearer. As a result, it is obvious that thetexture improves, and there is little risk that the side portions of thecover nonwoven fabric are peeled off by movement of the legs. In thiscase, the liquid impervious sheet is concealed by the cover nonwovenfabrics and the gather nonwoven fabric, and the side portions of thecover nonwoven fabric are covered with the gather nonwoven fabrics.However, when the total luminous transmittance of the gather nonwovenfabric is 60 to 90%, even in the portions where the gather nonwovenfabrics hide the cover nonwoven fabric, since the holes of theperforated nonwoven fabric are transparent and can be visuallyrecognized sufficiently, it can be recognized that a portion having theair-permeability-improving function extends to the side gathers, and thevisual effect of the holes can be sufficiently exhibited.

Advantageous Effects of Invention

As described above, the present invention provides advantages such asimproving the visual effect of holes when a perforated nonwoven fabricis used for a cover nonwoven fabric in an outer member separated-typeunderpants-type disposable diaper.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an inner surface of an underpants-typedisposable diaper in a spread state.

FIG. 2 is a plan view of an outer surface of an underpants-typedisposable diaper in a spread state.

FIG. 3 is a cross-sectional view taken along line 2-2 in FIG. 1.

FIG. 4 is a cross-sectional view taken along line 3-3 in FIG. 1.

FIG. 5(a) is a cross-sectional view taken along line 4-4 in FIG. 1, andFIG. 5(b) is a cross-sectional view taken along line 5-5 in FIG. 1.

FIG. 6 is a perspective view (holes are omitted) of an underpants-typedisposable diaper.

FIG. 7 is a plan view of an outer surface of an inner member in a spreadstate.

FIG. 8 is a plan view of an outer surface of an inner member in a spreadstate together with an outline of an outer member.

FIG. 9 is a plan view of an outer surface of an underpants-typedisposable diaper in a spread state.

FIG. 10(a) is a cross-sectional view taken along line 4-4 in FIG. 9, andFIG. 10(b) is a cross-sectional view taken along line 5-5 in FIG. 9.

FIG. 11 is a cross-sectional view taken along line 2-2 in FIG. 1according to another embodiment.

FIG. 12 is a cross-sectional view taken along line 2-2 in FIG. 1according to another embodiment.

FIG. 13 is a cross-sectional view taken along line 3-3 in FIG. 1according to another embodiment.

FIG. 14(a) is a perspective view of a hole of a perforated nonwovenfabric, FIG. 14(b) is a plan view thereof, and FIG. 14(c) is across-sectional view taken along line 1-1.

FIG. 15(a) is a perspective view of a hole of a perforated nonwovenfabric, FIG. 15(b) is a plan view thereof, and FIG. 15(c) across-sectional view taken along line 1-1.

FIG. 16(a) is a perspective view of a hole of a perforated nonwovenfabric, FIG. 16(b) is a plan view thereof, and FIG. 16(c) is across-sectional view taken along line 1-1.

FIG. 17 is an enlarged plan view of a main part of a perforated nonwovenfabric.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. A dotted patternportion in the cross-sectional view indicates an adhesive as joiningmeans for joining constituent members positioned on a front surface sideand a back surface side thereof. The dotted pattern portion is formed bysolid, bead, curtain, summit, or spiral application of a hot meltadhesive, pattern coating (transfer of a hot melt adhesive in aletterpress method), or the like. Alternatively, in a fixed portion ofeach elastic member, instead of or together with the above, the dottedpattern is formed by application with a comb gun or a SureWrap nozzle onan outer peripheral surface of the elastic member. Examples of the hotmelt adhesive include, but are not limited to, adhesives of the EVAtype, adhesive rubber type (elastomer), olefin, and polyester/polyamide.As a joining means for joining each constituent member, a means bymaterial welding such as heat sealing or ultrasonic sealing can also beused.

FIGS. 1 to 6 illustrate an underpants-type disposable diaper. Thisunderpants-type disposable diaper includes a front side outer member 12Fdisposed in a front body F, a back side outer member 12B disposed in aback body B, and an inner member 200 provided inside of the outermembers 12F and 12B so as to extend from the front side outer member 12Fto the back side outer member 12B through a crotch portion. Side sealportions 12A are formed by joining both sides of the front side outermember 12F and both side of the back side outer member 12B. Therefore,an opening formed by front and back end portions of the outer members12F and 12B becomes a waist opening WO through which the lower torso ofa wearer passes and portions surrounded by lower edges of the outermembers 12F and 12B and side edges of the inner member 200 on both sidesof the inner member 200 in the width direction become leg openings LOthrough which the legs pass. The inner member 200 is a portion thatabsorbs and holds excrement such as urine, and the outer members 12F and12B are portions for supporting the inner member 200 with respect to thebody of a wearer. The reference sign Y denotes the maximum length of adiaper in a spread state (the length in the front-back direction from anedge of the waist opening WO of the front body F to an edge of the waistopening WO of the back body B), and the reference sign X denotes themaximum width of a diaper in a spread state.

In addition, the underpants-type disposable diaper of this embodimentincludes a lower torso region T and an intermediate region L. The lowertorso region T is defined as a range in the front-back direction havingside seal portions 12A (a region in the front-back direction from thewaist opening WO to upper ends of the leg openings LO). The intermediateregion L is defined as a range in the front-back direction of a portionforming the leg openings LO (between the region in the front-backdirection having the side seal portions 12A of the front body F and theregion in the front-back direction having the side seal portions 12A ofthe back body B). The lower torso region T can be divided into a “waistportion” W which conceptually forms an edge portion of a waist openingand an “under-waist portion” U which is a portion lower than the waistportion W. Normally, in the case of having a boundary where stretchingstress in the width direction WD changes in the lower torso region T(for example, in the case where the fineness and stretch rate of eachelastic members change), a portion nearer to the waist opening WO than aboundary closest to the waist opening WO is the waist portion W. Whenthere is no such boundary, the waist opening WO side of an absorber 56or the inner member 200 is the waist portion W. A length in thefront-back direction varies depending on the size of a product and canbe appropriately determined. For example, the waist portion W can be setto 15 to 40 mm, and the under-waist portion U can be set to 65 to 120mm. On the other hand, both side edges of the intermediate region L arenarrowed along the periphery of the legs of a wearer in a channel shapeor a curved shape to form portions through which the wearer's legs pass.As a result, the underpants-type disposable diaper in a spread state hasa substantially hourglass shape as a whole.

(Inner Member)

The inner member 200 can have an arbitrary shape, but in the illustratedembodiment, it is rectangular. As illustrated in FIGS. 3 to 5, the innermember 200 is provided with a top sheet 30 on the body side, a liquidimpervious sheet 11, and an absorbent element 50 interposedtherebetween, and is a main unit section that plays a role of anabsorbent function. The reference sign 40 denotes an intermediate sheet(second sheet) provided between the top sheet 30 and the absorbentelement 50 in order to promptly transfer liquid having permeated throughthe top sheet 30 to the absorbent element 50. The reference sign 60denotes side gathers 60 extending from both sides of the inner member200 so as to be in contact with the legs of a wearer in order to preventexcrement from leaking to the both sides of the inner member 200.

(Top Sheet)

The top sheet 30 has a property of permeating liquid, and examples ofthe top sheet 30 include a perforated or non-perforated nonwoven fabricand a porous plastic sheet. Among them, a raw fiber of the nonwovenfabric is not particularly limited. Examples of the raw fiber includesynthetic fibers such as olefin such as polyethylene and polypropylene,polyester, and polyamide, regenerated fibers such as rayon and cupra,natural fibers such as cotton, and mixed fibers and composite fibers inwhich two or more of these are used. Further, the nonwoven fabric may bemanufactured by any processing. Examples of the processing methodinclude known methods such as a spun lace method, a spunbond method, athermal bond method, a melt blown method, a needle punch method, anair-through method, and a point bond method. For example, if flexibilityand drapeability are required, the spunbond method and the spun lacemethod are preferable processing methods, and if bulkiness and softnessare required, the air-through method, the point bond method, and thethermal bond method are preferable processing methods.

Further, the top sheet 30 may be made of one sheet or a laminated sheetobtained by bonding two or more sheets. Similarly, the top sheet 30 maybe composed of one sheet or two or more sheets with respect to the planedirection.

Both sides of the top sheet 30 may be folded back to the back surfaceside at side edges of the absorbent element 50 or protruded laterallybeyond the side edges of the absorbent element 50 without folding back.

For the purpose of preventing positional deviation of the top sheet withrespect to a member on the back surface side thereof, it is desirablethat the top sheet 30 be fixed to a member adjacent to the back surfaceside by joining means such as heat sealing or ultrasonic sealingmaterial welding or by a hot melt adhesive. In the illustratedembodiments, the top sheet 30 is fixed to the surface of theintermediate sheet 40 and an area on the surface of the wrapping sheet58, which is located on a front surface side of the absorber 56, by ahot melt adhesive applied on a back surface of the top sheet 30.

(Intermediate Sheet)

In order to quickly transfer the liquid having permeated through the topsheet 30 to the absorber, it is possible to provide the intermediatesheet (also referred to as “second sheet”) 40 having a higher liquidpermeation rate than the top sheet 30. This intermediate sheet 40 notonly improves the absorption performance by an absorber by immediatelymoving liquid to the absorber, but also prevents “returning” phenomenonof the absorbed liquid from the absorber to make a surface of the topsheet 30 dry constantly. The intermediate sheet 40 can also be omitted.

Examples of the intermediate sheet 40 include the same material as thetop sheet 30, a spun lace, a spunbond, SMS, a pulp nonwoven fabric, amixed sheet of pulp and rayon, a point bond, or crepe paper. Inparticular, an air-through nonwoven fabric is preferable because it isbulky. It is preferable to use a composite fiber having a core-sheathstructure for the air-through nonwoven fabric. In this case, resin usedfor the core may be polypropylene (PP), but polyester (PET) having highrigidity is preferable. The basis weight is preferably 20 to 80 g/m²,more preferably 25 to 60 g/m². The fineness of the raw fiber of thenonwoven fabric is preferably 2.0 to 10 dtex. To increase the bulkinessof the nonwoven fabric, it is also preferable to use eccentric fibers,hollow fibers, eccentric and hollow fibers, whose core is not in thecenter, as mixed fibers of all or a part of the raw material fibers.

The intermediate sheet 40 in the illustrated embodiment is disposed atthe center having the width shorter than the width of the absorber 56,but may be provided throughout the maximum width of the absorber 56. Thelength of the intermediate sheet 40 in the longitudinal direction may bethe same as the length of the absorber 56 or may be within a shortlength range centering on a region receiving a liquid.

For the purpose of preventing positional deviation of the intermediatesheet with respect to a member on the back surface side thereof, it isdesirable that the intermediate sheet 40 be fixed to a member adjacentto the back surface side by joining means such as heat sealing orultrasonic sealing material welding or by a hot melt adhesive. In theillustrated embodiments, the intermediate sheet 40 is fixed to thesurface of an area of the wrapping sheet 58, which is positioned on afront surface side of the absorber 56, by a hot melt adhesive applied onthe back surface of the intermediate sheet 40.

(Liquid Impervious Sheet)

The material of the liquid impervious sheet 11 is not particularlylimited, but examples of the material include a plastic film made of anolefin resin such as polyethylene and polypropylene, a laminatednonwoven fabric having a plastic film on the surface of a nonwovenfabric, and a laminated sheet obtained by joining nonwoven fabrics orthe like on a plastic film. In the liquid impervious sheet 11, it ispreferable to use a material having liquid impermeability and moisturepermeability that has been favorably used from the viewpoint ofprevention of stuffiness. As the moisture-permeable plastic film, amicroporous plastic film is widely used. The microporous plastic film isobtained by stretching a sheet in a monoaxial or biaxial direction afterforming the sheet by kneading an inorganic filler in an olefin-basedresin such as polyethylene or polypropylene. In addition to this, anonwoven fabric of a micro-denier fiber and a liquid impervious sheetwithout a plastic film having reinforced leakage-resistance achieved byapplying heat and pressure to reduce the gaps between the fibers or byapplication with super absorbent resin, a hydrophobic resin, or a waterrepellent agent can also be used as the liquid impervious sheet 11.

The liquid impervious sheet 11 may have a width that fits on the backsurface side of the absorbent element 50 as illustrated in the drawing.Alternatively, to enhance leakage resistance, the liquid impervioussheet 11 may be disposed around both sides of the absorbent element 50to extend to both sides of the surface of the top sheet 30 side of theabsorbent element 50. It is appropriate that the width of this extendingportion is about 5 to 20 mm for the right side and the left side.

Further, on the inside of the liquid impervious sheet 11, in particular,on the surface of the absorber 56 side, an excretion indicator thatchanges its color due to absorption of a liquid component can beprovided.

(Side Gather)

The side gathers 60 extend throughout the whole front-back direction LDalong both sides of the inner member 200 and are provided to contact thelegs of a wearer and prevent side leakage. In general, the side gather60 is a gather called a three-dimensional gather or a flat gather.

The side gathers 60 of the first embodiment illustrated in FIGS. 3 and 4are so-called three-dimensional gathers and standing from side portionsto a front surface side of the inner member 200. In each of the sidegathers 60, a root-side portion stands diagonally toward the center inthe width direction, and a portion closer to a tip than to theintermediate portion stands diagonally outward in the width direction,but the configuration is not limited to this and can be appropriatelychanged to a structure of standing toward the center in the widthdirection as a whole or the like.

To be more specific, the side gather 60 according to the firstembodiment is formed by folding back and being folded in two, in thewidth direction WD at a tip portion, a belt shaped gather nonwovenfabric 62 having a length equal to the length in the front-backdirection of the inner member 200, and a plurality of elongated gatherelastic members 63 are fixed with intervals in the width direction WD ina stretched state along the longitudinal direction between the foldedback portion and an adjacent sheet. A base portion located on theopposite side to a tip portion of the side gather 60 (the end portion onthe side opposite to a sheet folded back portion in the width directionWD) is a root portion 65 fixed to a side portion on the back surfaceside of the liquid impervious sheet 11 in the inner member 200, and aportion other than the root portion 65 is a main unit section 66 (aportion on the folded back portion side) extending from the root portion65. The main unit section 66 includes a base side portion directedtoward the center in the width direction and a tip side portion foldedback outward in the width direction from a tip of the base side portion.Although this embodiment is a surface contact-type side gather 60, aline contact-type side gather 60 which is not folded back outward in thewidth direction can also be used. Both end portions of the main unitsection 66 in the front-back direction are set to be fallen parts 67fixed to a surface of a side portion of the top sheet 30 in a fallenstate, while an intermediate portion in the front-back directionpositioned therebetween is a non-fixed free portion 68, and gatherelastic members 63 along the front-back direction LD are fixed to thefree portion 68 in a stretched state.

As the gather nonwoven fabric 62, a nonwoven fabric which is flexibleand excellent in uniformity and concealing property such as a spunbondednonwoven fabric (SS, SSS, etc.), SMS nonwoven fabric (SMS, SSMMS, etc.),meltblown nonwoven fabric, and on which a water repellent process isperformed by silicone as necessary, can be suitably used, and the fiberbasis weight is preferably set to about 10 to 30 g/m². As the gatherelastic member 63, a rubber thread or the like can be used. When aspandex rubber thread is used, the fineness is preferably 470 to 1240dtex, more preferably 620 to 940 dtex. The stretch rate at the time offixing is preferably 150 to 350%, more preferably 200 to 300%. The term“stretch rate” means a value when the natural length is taken as 100%.As illustrated in the drawing, a waterproof film 64 may be interposedbetween the gather nonwoven fabrics 62 folded in two. In this case, thegather nonwoven fabric 62 may be partially omitted in the portion wherethe waterproof film 64 is present. However, in order to make theappearance and feel of a product like a cloth, it is necessary that atleast an outer surface from a base end to a tip of the side gather 60 isformed of the gather nonwoven fabric 62 as the illustrated embodiment.

The number of the gather elastic members 63 provided in the free portionof the side gather 60 is preferably two to six, more preferably three tofive. An appropriate arrangement interval 60 d is 3 to 10 mm With such aconfiguration, a range in which the gather elastic members 63 aredisposed easily comes into surface contact with the skin. The gatherelastic member 63 may be disposed not only on the tip side but also onthe root side.

In the free portion 68 of the side gather 60, at least one of a hot meltadhesive by various application methods and a fixing means by materialwelding such as heat seal or ultrasonic seal can be used for bonding aninner layer and an outer layer of the gather nonwoven fabric 62 and forfixing the gather elastic members 63 sandwiched therebetween. Since theflexibility is impaired when the whole surface of the inner layer andwhole surface of the outer layer of the gather nonwoven fabric 62 arefixed each other, it is preferable that an area other than the bondedportions of the gather elastic members 63 be not bonded or be weaklybonded. In the illustrated embodiment, by applying a hot melt adhesiveonly to outer peripheral surfaces of the gather elastic members 63 by anapplication means such as a comb gun or a SureWrap nozzle andsandwiching the gather elastic members between the inner layer and theouter layer of the gather nonwoven fabric 62, fixation of the gatherelastic members 63 to the inner layer and the outer layer of the gathernonwoven fabric 62 and fixation between the inner layer and the outerlayer of the gather nonwoven fabric 62 are performed by using only thehot melt adhesive applied to the outer peripheral surfaces of the gatherelastic members 63.

Further, for fixation of the waterproof film 64, which has beenincorporated in the side gather 60, and the gather nonwoven fabric 62and fixation of the fallen parts 67 to the surface of the side portionof the inner member 200, at least one of a hot melt adhesive by variousapplication methods and material welding such as heat sealing andultrasonic sealing can be used. In the illustrated embodiment, slotapplication of a hot melt adhesive is used for fixing the waterprooffilm 64. In addition, to fix the fallen parts 67 in the illustratedembodiment, the means of a hot melt adhesive and the means of materialwelding are combined, but these fixation can be carried out by eitherone of these means.

The fixing target of the root portion 65 of the side gather 60 can be anappropriate member such as the top sheet 30, the liquid impervious sheet11, and the absorbent element 50 in the inner member 200.

In the side gather 60 according to the first embodiment formed asdescribed above, a contraction force of the gather elastic members 63acts so as to bring both end portions of the side gather in thefront-back direction close to each other, but both end portions in thefront-back direction of the main unit section 66 are fixed not to erect,and a space between the both ends is a non-fixed free portion.Therefore, only the free portion stands so as to come into contact withthe body side as illustrated in FIG. 3 by two-dot chain line arrows.Particularly, when the root portion 65 is positioned on the back surfaceside of the inner member 200, the side gathers 60 stand so as to openoutward in the width direction at and around a crotch portion, such thatthe side gathers 60 come into surface contact with a leg portion, andtherefore, the fitting is improved.

Although the dimension of the side gather 60 according to the firstembodiment can be appropriately determined, in the case of an infantdisposable diaper, as illustrated in FIG. 3, for example, the erectionheight of the side gather 60 (the width direction length of the mainunit section 66 in a spread state) W6 is preferably 15 to 60 mm,particularly 20 to 40 mm. Further, in a state where the side gathers 60are folded flat so as to be parallel to a surface of the top sheet 30,it is preferable that the distance W3 between the innermost folds be 60to 190 mm, particularly 70 to 140 mm

Although the side gathers 60 of the first embodiment include onlythree-dimensional gathers, they may include both three-dimensionalgathers and flat gathers or may include only flat gathers. FIGS. 12 and13 illustrate the side gathers 60 according to the second embodiment,including both three-dimensional gathers and flat gathers. Each of theside gathers 60 has a first portion 61 (flat gather portion) and asecond portion 69 (three-dimensional gather portion). The first portion61 protrudes to the side of the inner member 200 from the root portion65 fixed to a side portion of the inner member 200 on the back surfaceside of the liquid impervious sheet 11. The second portion 69 protrudesto the front surface side of the inner member 200 from a portion of theroot portion 65 fixed to each of both sides of the top sheet 30 in theinner member 200. More specifically, a belt shaped gather nonwovenfabric 62 having a length equal to the length in the front-backdirection of the inner member 200 extends laterally from the rootportion 65 and is folded back to the front surface side at a tip of thefirst portion 61, and the portion folded back to the front surface sidereaches the second portion 69 via the first portion 61 and is foldedback at a tip of the second portion 69. In the folded portion of thegather nonwoven fabric 62, opposing portions are joined by a hot meltadhesive or the like. Further, both end portions in the front-backdirection of the second portion 69 are the fallen parts 67 fixed to aside surface of the top sheet 30 in a fallen state. On the other hand,the intermediate portion in the front-back direction positioned betweenthe both ends is a non-fixed free portion 68. At least in theintermediate portion in the front-back direction of the first portion 61and in the free portion 68 of the second portion 69, one gather elasticmember 63 or a plurality of the gather elastic members 63 with intervalsin the width direction WD are fixed in a stretched state along thefront-back direction LD. Due to a contraction force thereof, the freeportion 68 of the second portion 69 contracts in the front-backdirection LD and becomes a three-dimensional gather in contact with theleg, and also the first portion 61 contracts in the front-back directionLD and becomes a flat gather in contact with the leg.

Other points relating to the second embodiment, for example, a materialof the gather nonwoven fabric 62, a material of the gather elasticmember 63, and the like are the same as those in the first embodiment,and therefore, the description will be omitted.

(Absorbent Element)

The absorbent element 50 has the absorber 56 and a wrapping sheet 58wrapping the entire absorber 56. The wrapping sheet 58 can also beomitted.

(Absorber)

The absorber 56 can be formed of an assembly of fibers. As this fiberassembly, besides those obtained by accumulating short fibers such asfluff pulp and synthetic fibers, a filament assembly obtained by openingtows (fiber bundles) of synthetic fibers such as cellulose acetate asrequired can also be used. When fluff pulp or short fibers areaccumulated, fiber basis weight can be set to, for example, about 100 to300 g/m², and in the case of a filament assembly, fiber basis weight canbe set to about 30 to 120 g/m². In the case of a synthetic fiber, thefineness is, for example, 1 to 16 dtex, preferably 1 to 10 dtex, morepreferably 1 to 5 dtex. In the case of filament assembly, the filamentsmay be non-crimped fibers, but are preferably crimped fibers. The degreeof crimp of the crimped fiber can be, for example, about 5 to 75 crimps,preferably about 10 to 50 crimps, and more preferably about 15 to 50crimps per inch. In addition, crimped fibers which are uniformly crimpedare often used. It is preferable to disperse and hold the superabsorbent polymer particles in the absorber 56.

The absorber 56 may have a rectangular shape, and, as illustrated inFIG. 7, preferably has a shape similar to the outline of an hourglasswhich has a front end portion, a back end portion and a narrowingportion 56N positioned between the front end portion and the back endportion and having narrower width than that of the front end portion andthat of the back end portion, since the fitting of the absorber 56itself and the side gathers 60 around the legs is improved.

Further, although the size of the absorber 56 can be appropriatelydetermined as long as the absorber 56 extends throughout the front,back, right and left sides with respect to an excreted position ofurine, it is preferable that the absorber 56 extend to or nearperipheral edge portion of the inner member 200 in the front-backdirection LD and the width direction WD. The reference sign 56X denotesthe width of the absorber 56.

(Super Absorbent Polymer Particle)

The absorber 56 can contain super absorbent polymer particles partiallyor entirely. The super absorbent polymer particle includes “powder” inaddition to “particle”. The super absorbent polymer particles 54 usedfor this kind of disposable diapers can be used as they are, and forexample, screened with a sieve (shaking for 5 minutes) using a standardsieve of 500 μm (JIS Z 8801-1: 2006), and the proportion of particlesremaining on the sieve is desirably 30% by weight or less. Further, theproportion of particles remaining on the sieve by screening (shaking for5 minutes) using a standard sieve of 180 μm (JIS Z 8801-1: 2006) isdesirably 60% by weight or more.

The material of the super absorbent polymer particles is notparticularly limited, but materials having a water absorption capacityof 40 g/g or more are suitable. Examples of the super absorbent polymerparticles include starch-based, cellulose-based, and syntheticpolymer-based particles, and starch-acrylic acid (salt) graftcopolymers, saponified starch-acrylonitrile copolymers, crosslinkedsodium carboxymethylcellulose, and acrylic acid (salt) polymers can beused. As the shape of the super absorbent polymer particles, particulatematerials which are usually used are preferable, but other shapes canalso be used.

The super absorbent polymer particles having a water absorption rate of70 seconds or less, particularly 40 seconds or less, are suitably used.If the water absorption rate is too slow, so-called returning, in whichthe liquid fed into the absorber 56 returns to the outside of theabsorber 56, is likely to occur.

As the super absorbent polymer particles, those having a gel strength of1000 Pa or more are suitably used. Thereby, even when the absorber 56 isbulky, it is possible to effectively suppress stickiness after liquidabsorption.

The basis weight of the super absorbent polymer particles can beappropriately determined according to the absorption amount required forthe use of the absorber 56. Therefore, although it cannot be saidunconditionally, the basis weight can be 50 to 350 g/m². When the basisweight of the polymer is less than 50 g/m², it is difficult to ensurethe absorption amount. When it exceeds 350 g/m², the effect issaturated.

If necessary, the super absorbent polymer particles can adjust aspraying density or a spraying amount in the planar direction of theabsorber 56. For example, it is possible to increase the spraying amountin an excretory site of liquid compared to the other sites. Whenconsidering the difference between men and women, it is possible toincrease the spray density (amount) on the front side for men and toincrease the spray density (amount) at the center for women. Further, aportion without polymer can be provided locally (for example, in a spotshape) in the planar direction of the absorber 56.

(Wrapping Sheet)

When the wrapping sheet 58 is used, tissue paper, particularly crepepaper, a nonwoven fabric, a polyethylene laminated nonwoven fabric, asheet with small openings can be used as the material. However, it isdesirable that the sheet from which the super absorbent polymerparticles do not come off be used. When a nonwoven fabric is used inplace of crepe paper, a hydrophilic SMS nonwoven fabric (SMS, SSMMS,etc.) is particularly suitable, and polypropylene,polyethylene/polypropylene composite material, and the like can be usedas the material. The basis weight is desirably 5 to 40 g/m²,particularly desirably 10 to 30 g/m².

The wrapping mode of the wrapping sheet 58 can be appropriatelydetermined. However, from the viewpoints of ease of manufacturing andprevention of leakage of highly absorbent polymer particles from thefront and back end edges, it is preferable that the wrapping sheet 58 bewound around in a cylindrical shape so as to surround the front and backsurfaces and both side surfaces of the absorber 56, the front and backedge portions are protruded from the front and back of the absorber 56,and an overlapping portion of the wound sheet and the protrudingportions be joined by a joining means such as a hot melt adhesive andmaterial welding.

(Indicator)

On the absorber 56 side of the liquid impervious sheet 11, it ispossible to provide an indicator 80 which changes color by contact witha liquid content of excrement. The indicator 80 includes a sheet-likemember that contains a coloring agent which indicates a color reactionby contact with a liquid content of excrement and/or a coloring agentwhich indicates a color reaction by detecting the pH in moisture, an inkor an adhesive containing other agents that indicate a reaction in whichcoloration disappears by reaction with a body fluid, a reaction blurredor disappeared since a coloring agent is dissolved (dispersed) by urine,and other visual changes, or an agent (indicator reaction means) thatindicates a visual change by contact with moisture or a body fluid. Forexample, as a coloring agent that indicates a color reaction by contactwith moisture such as a body fluid, the color agent can be used whichcontains a water-soluble, water-decomposable dye or a leuco dye and adeveloper such as a phenolic compound for coloring the leuco dye, acidicsubstances, or an electron accepting substance.

The color appearing due to coloration is not particularly limited, butwhen it is the same color as the outer surface of a diaper (normallywhite), it is difficult to recognize the coloration. Therefore, it issuitable to use a color of coloration different from that of the outersurface of a diaper.

As illustrated in FIGS. 2 and 3, the indicator 80 including theabove-described ink or adhesive is applied to a predeterminedapplication region. Note that the indicator 80 illustrated in FIGS. 2and 3 shows an application region of the above-described ink oradhesive. This region is preferably included in a disposition range ofthe absorber 56, is located at the center in the width direction, andhas a width of about 0.2 to 5 cm, preferably about 0.4 to 2 cm and alength of 20 to 70% of the maximum length L of a diaper. Contact withexcrement absorbed by the absorber 56 is efficiently performed in thisregion. The indicator 80 is desirably formed by applying an ink or anadhesive included in the indicator 80 between a back surface of theabsorber 56 and the liquid impervious sheet 11, specifically on a sidesurface of the absorber 56 of the liquid impervious sheet 11 or an innersurface or outer surface of the wrapping sheet 58. The applicationpattern is not particularly limited, and it may be a band shape asillustrated in FIG. 7, or it may be applied in a pattern of a planeshape or other figures, in addition to a pattern with a large number ofstreaks. It is preferable that in the case of a belt-shaped pattern, theapplication width be 2 to 5 mm, and in the case of the pattern with alarge number of streaks, the application width per streak is 1 to 2 mm,and about 2 to 4 strips are arranged at intervals of about 0.5 to 1.5mm. It is obviously possible to separately manufacture a sheet on whichthe indicator 80 is formed and incorporate the sheet-like indicator 80in a diaper. The indicator 80 is preferably disposed at a distance of 5mm or more, particularly 10 mm or more, from decorative printing to bedescribed later, since its discoloration is easily found.

When the indicator 80 is composed of an ink, the component of theindicator 80 is an ink in which a coloring agent is added. When theindicator 80 is composed of an adhesive, the component of the indicator80 is an adhesive in which a water-insoluble polymer made of a resin andthe like and a coloring agent are added to a water soluble polymer or ahydrophilic polymer. Specifically, in the case of being composed of anadhesive, a water-soluble polymer including a polyethylene glycol withmolecular weight of 100 to 500, polyvinylpyrrolidone/vinyl acetatecopolymer, and a water-soluble polyester, a water insoluble component ofa highly polar tackifier resin and a plasticizer, and a coloring agentwhich indicates the degree of acidity/alkalinity (pH) of a liquid to becontacted by discoloration are included.

When the indicator 80 is made of an adhesive, various known adhesivescan be used as the adhesive. As an example thereof, the case of using ahot melt adhesive will be described in detail. By using a hot meltadhesive containing a coloring agent as the indicator 80, it is possibleto prevent diffusion and leaching of the coloring agent and the like.Further, compared to the case where a sheet-like indicator is provided,since it can be easily carried out in manufacturing line, it is possibleto drastically reduce work process for attaching the indicator.

On the other hand, when the indicator 80 made of a sheet-like member isused, the sheet-like member is disposed between the liquid impervioussheet 11 and the absorber 56, specifically between the absorber 56 andthe inner surface of the wrapping sheet 58 or between the back surfaceof the wrapping sheet 58 and the liquid impervious sheet 11. Note thatwhen this sheet-like indicator 80 is used, the number of members isincreased as compared with the case where the liquid indicator 80 isapplied, but only the necessary amount can be easily used at thenecessary sites, and the cost can be reduced by reducing the use area ofthe sheet-like member including an indicator reaction means.

(Outer Member)

The outer members 12F and 12B include the front side outer member 12Fdisposed in the front body F and the back side outer member 12B disposedin the back body B. The front side outer member 12F and the back sideouter member 12B are not continuous on the crotch side but areseparately provided in the front-back direction LD. The separationdistance 12 d can be, for example, about 150 to 250 mm

The outer members 12F and 12B have lower torso portions which are rangesin the front-back direction, corresponding to the lower torso region T.In the present embodiment, the front side outer member 12F does not havea portion corresponding to the intermediate region L, but the back sideouter member 12B has a gluteal cover portion C extending from the lowertorso region T to the intermediate region L side. Although notillustrated, the front side outer member 12F may also be provided withan inguinal cover portion extending from the lower torso region T towardthe intermediate region L side; even though the inguinal cover portionis provided, a gluteal cover portion may not be provided; or both thefront side outer member 12F and the back side outer member 12B are notnecessarily provided with a portion corresponding to the intermediateregion L. Further, in the illustrated embodiment, the lower edge of thegluteal cover portion C is formed in a straight line along the widthdirection WD similarly to the lower edge of the front side outer member12F. However, the lower edge of the gluteal cover portion C may beformed in a curved line such that the outer ends of the lower edge inthe width direction are closing toward the waist opening.

As illustrated in FIGS. 4 and 5, the outer members 12F and 12B areformed by joining the outer sheet layer 12S and the inner sheet layer12H by a joining means such as a hot melt adhesive or welding. A sheetmaterial forming the outer sheet layer 12S and a sheet material formingthe inner sheet layer 12H may be a common sheet material as in theembodiment of FIG. 5 or may be individual sheet materials. That is, inthe former case, each of the inner sheet layer 12H and the outer sheetlayer 12S is formed by the inner portion and the outer portion of onesheet material folded back at the edge of the waist opening WO (whichmay be a crotch side edge). The former structure has an advantage thatthe inner sheet layer 12H and the outer sheet layer 12S are not easilydisplaced when those are laminated. The latter structure has anadvantage that the number of materials of the sheet material can bereduced.

A sheet material used for the outer sheet layer 12S and the inner sheetlayer 12H can be used without particular limitation, but a nonwovenfabric is preferable, and for example, a nonwoven fabric composed ofsynthetic fibers such as olefin such as polyethylene and polypropylene,polyester, polyamide, and a nonwoven fabric composed of a mixed fiber, acomposite fiber, or the like in which two or more of the above are usedcan be used. Further, the nonwoven fabric may be manufactured by anyprocessing. Examples of the processing method include known methods suchas a spun lace method, a spunbond method, a thermal bond method, a meltblown method, a needle punch method, an air-through method, and a pointbond method. When a nonwoven fabric is used, its basis weight ispreferably about 10 to 30 g/m².

Further, the total basis weight of the outer members 12F and 12B ispreferably about 20 to 60 g/m².

(Stretchable Region/Non-stretchable Region)

The elongated elastic members 15 to 19 such as rubber threads or thelike are provided between the outer sheet layer 12S and the inner sheetlayer 12H to improve the fitting to the lower torso of a wearer on theouter members 12F and 12B. A stretchable region, which is elasticallystretchable in the width direction WD with the elasticity of the elasticmembers, is formed. In this stretchable region, in the state of naturallength, the outer sheet layer 12S and the inner sheet layer 12H contractas the elastic members contract, and wrinkles or folds are formed. Whenthe stretchable region is stretched in the longitudinal direction of theelastic member, the outer sheet layer 12S and the inner sheet layer 12Hcan be stretched to a predetermined stretch rate at which the outersheet layer 12S and the inner sheet layer 12H stretch without wrinkle.As the elastic members 15 to 19, synthetic rubber may be used, and alsonatural rubber may be used.

For bonding the outer sheet layer 12S and the inner sheet layer 12H inthe outer members 12F and 12B and fixing the elastic members 15 to 19sandwiched therebetween, at least one of a hot melt adhesive by variousapplication methods and a fixing means by material welding such as heatseal or ultrasonic seal can be used. Since the flexibility is impairedwhen the whole outer members 12F and 12B are firmly fixed, it ispreferable that the area other than the bonded portions of the elasticmembers 15 to 19 be not bonded or be weakly bonded. In the illustratedembodiment, a hot-melt adhesive is applied only to the outer peripheralsurfaces of the elastic members 15 to 19 by an application means such asa comb gun or a SureWrap nozzle and is sandwiched between both the sheetlayers 12S and 12H, whereby the elastic members 15 to 19 are fixed toboth the sheet layers 12S and 12H, and the both sheet layers 12S and 12Hare fixed by using only the hot melt adhesive applied to the outerperipheral surfaces of the elastic members 15 to 19. The elastic members15 to 19 can be fixed to the outer sheet layer 12S and the inner sheetlayer 12H only at both end portions in a stretchable direction in thestretchable region.

More specifically, between the outer sheet layer 12S and the inner sheetlayer 12H in the waist portion W of the outer members 12F and 12B, aplurality of the waist portion elastic members 17 are attached atintervals in an up-down direction so as to extend in the whole widthdirection WD. Among the waist portion elastic members 17, one or aplurality of the waist portion elastic members 17 disposed in a regionadjacent to the under-waist portion U may overlap with the inner member200 or may be provided on both sides in the width direction except forthe central portion in the width direction overlapping with the innermember 200. As these waist portion elastic members 17, about three totwenty two rubber threads having a fineness of about 155 to 1880 dtex,particularly about 470 to 1240 dtex (in the case of synthetic rubber),(a cross-sectional area is about 0.05 to 1.5 mm², particularly about 0.1to 1.0 mm² in the case of natural rubber) are preferably provided at aninterval of 4 to 12 mm, and accordingly a stretch rate of the widthdirection WD of the waist portion W is preferably about 150 to 400%,particularly about 220 to 320%. In addition, it is unnecessary to usethe waist portion elastic members 17 having the same thickness in thewhole front-back direction LD in the waist portion W or to set to thesame stretch rate. For example, at an upper portion and a lower portionof the waist portion W, the elastic member 17 may be different inthickness and the stretch rate.

Between the outer sheet layer 12S and the inner sheet layer 12H in theunder-waist portion U of the outer members 12F and 12B, a plurality ofunder-waist portion elastic members 15 and 19 formed of elongatedelastic members are attached at intervals in the up-down direction.

As the under-waist portion elastic members 15 and 19, five to thirtyrubber threads each having a fineness of about 155 to 1880 dtex,particularly about 470 to 1240 dtex (in the case of synthetic rubber),(a cross-sectional area is about 0.05 to 1.5 mm², particularly about 0.1to 1.0 mm² in the case of natural rubber) are preferably provided at aintervals of 1 to 15 mm, particularly 3 to 8 mm, and accordingly astretch rate of the width direction WD of the under-waist portion U ispreferably about 200 to 350%, particularly about 240 to 300%.

Further, between the outer sheet layer 12S and the inner sheet layer 12Hin the gluteal cover portion C of the back side outer members 12B, aplurality of cover portion elastic members 16 formed of elongatedelastic members are attached at intervals in the up-down direction.

As the cover portion elastic members 16, about two to ten rubber threadshaving a fineness of about 155 to 1880 dtex, particularly about 470 to1240 dtex (in the case of synthetic rubber), (a cross-sectional area isabout 0.05 to 1.5 mm², particularly about 0.1 to 1.0 mm² in the case ofnatural rubber) are preferably provided at intervals of 5 to 40 mm,particularly 5 to 20 mm, and accordingly a stretch rate of the widthdirection WD of the cover portion is preferably about 150 to 300%,particularly about 180 to 260%.

Similarly, in the case where an inguinal cover portion is provided onthe front side outer member 12F, it is possible to provide the coverportion elastic members.

Like the under-waist portion U and the gluteal cover portion C in theillustrated embodiment, when the elastic members 15, 16, and 19 areprovided in the range in the front-back direction having the absorber56, in order to prevent a part of or the whole of the absorber 56 fromcontracting in the width direction WD, a middle in the width direction(preferably including the entire inner and outer joined portion 201)including a part or the whole of the portion overlapping with theabsorber 56 in the width direction WD is set to a non-stretchable regionA1, and the both sides in the width direction thereof are set tostretchable regions A2. It is preferable that the waist portion W beformed as the stretchable region A2 throughout the whole width directionWD. However, similarly to the under-waist portion U, the non-stretchableregion A1 may be provided in the middle in the width direction.

The stretchable region A2 and the non-stretchable region A1 are providedwith the elastic members 15 to 17 and 19 between the inner sheet layer12H and the outer sheet layer 12S. The elastic members 15, 16, and 19are fixed at least at both end portions in the stretchable direction inthe stretchable region A2 with a hot melt adhesive and are not fixed inthe region to be the non-stretchable region A1. In a region to be thenon-stretchable region A1, the elastic members 15, 16, and 19 are cut bypressing and heating at one position at the middle in the widthdirection, or nearly the entire elastic members 15, 16, and 19 arefinely cut by applying pressure and heating. While leaving theelasticity in the stretchable region A2, the elasticity in thenon-stretchable region A1 is killed. In the former case, as illustratedin FIG. 4, in the non-stretchable region A1, residual portions continuedfrom the elastic members 15, 16, and 19 of the stretchable regions A2remain between the outer sheet layer 12S and the inner sheet layer 12Has idle elastic members 18 in a state where each idle elastic member 18is independently contracted to a natural length. In the latter case,although not illustrated, residual portions continued from the elasticmembers 15, 16, and 19 of the stretchable regions A2 and cut pieces ofthe elastic members separated from the elastic members 15, 16, and 19 ofthe both stretchable regions A2 remain between the outer sheet layer 12Sand the inner sheet layer 12H as idle elastic members in a state whereeach idle elastic member is independently contracted to natural length.

(Cover Nonwoven Fabric)

In the outer member separated-type underparts-type disposable diaper,the inner member 200 is exposed between the front side outer member 12Fand the back side outer member 12B. Therefore, in order that the liquidimpervious sheet 11 is not exposed on a back surface of the inner member200, the cover nonwoven fabric 13 that covers the back surface of theinner member 200 from between the front side outer member 12F and theinner member 200 to between the back side outer member 12B and the innermember 200 is provided.

The cover nonwoven fabric 13 can be fixed to the liquid impervious sheet11 and the gather nonwoven fabric 62 with a hot melt adhesive, and theapplication pattern of the hot melt adhesive is preferably a planarpattern such as a curtain, a summit, and a spiral. The fixing region ofthe cover nonwoven fabric 13 is the whole front-back direction and thewhole width direction of the cover nonwoven fabric 13, and a partthereof may be non-fixed. For example, when both the end portions in thewidth direction of the cover nonwoven fabric 13 are not fixed, there isan advantage that even in a state in which the side portions of theabsorber 56 are somewhat contracted due to the influence of the sidegathers 60, the cover nonwoven fabric 13 is not easily affected thereby,and wrinkles and folds are not easily formed on the cover nonwovenfabric 13. In this case, the width of the non-fixed portion at each ofboth the end portions in the width direction of the cover nonwovenfabric 13 may be appropriately determined, but it may be, for example, 3to 10 mm, preferably 5 to 8 mm

Characteristically, as the cover nonwoven fabric 13, a perforatednonwoven fabric is used in which a large number of holes 14 penetratingthe front surface and the back surface are provided at intervals. Thekind of fiber of the perforated nonwoven fabric and the method forbinding the fibers (for the entanglement) are not particularly limitedand the kind and method similar to those of the outer sheet can beappropriately selected, but it is desirable to use an air-throughnonwoven fabric. In such a case, the basis weight is preferably 20 to 40g/m², and the thickness is preferably 0.2 to 1.0 mm

The range of the cover nonwoven fabric 13 in the front-back direction isnot particularly limited as long as it has the portions overlapping withthe front side outer member 12F and the back side outer member 12B. Asillustrated in FIGS. 2, 5, 7, 9, and 10, the range of the cover nonwovenfabric 13 may extend in the front-back direction LD entirely from afront end to a back end of the inner member 200. As illustrated in FIG.8, it may extend in the front-back direction LD from an intermediateposition in the front-back direction of a region where the front sideouter member 12F and the inner member 200 overlap each other to anintermediate position in the front-back direction of a region where theback side outer member 12B and the inner member 200 overlap each other.In the latter case, a length 13 y in the front-back direction of theportion where the cover nonwoven fabric 13 and the front side outermember 12F overlap each other and the length 13 y in the front-backdirection of the portion where the cover nonwoven fabric 13 and the backside outer member 12B overlap each other can be appropriatelydetermined, but in the usual case, they can be each about 20 to 40 mm

The range in the width direction of the cover nonwoven fabric 13 is arange that can hide an exposed portion on a back surface of the liquidimpervious sheet 11. For this reason, in the illustrated embodiment,since the liquid impervious sheet 11 is exposed between the base ends ofthe left and right side gathers 60, the cover nonwoven fabric 13 isprovided so as to cover a width direction range from at least a backsurface side of the base portion of one side gather 60 to a back surfaceside of the base portion of the other side gather 60. Accordingly, theliquid impervious sheet 11 can be hidden with the cover nonwoven fabric13 and the gather nonwoven fabrics 62 of the side gathers 60, and whenviewed on the outer surface, the holes 14 at both end portions of thecover nonwoven fabric 13 in the width direction WD are not hidden by thegather nonwoven fabric 62. Further, when the side edges of the covernonwoven fabric 13 are located at positions same as the side edges of anarrowest part of the absorber 56 in the width direction (the full widthof the absorber when the narrowing portion 56N is not provided), (themaximum width of the narrowest portion of the narrowing portion 56N whenthe narrowing portion 56N is provided), or located at positions on thecenter side in the width direction with respect to the side edges of thenarrowest part, since the cover nonwoven fabric 13 is positioned suchthat the whole cover nonwoven fabric 13 overlaps with the absorber 56,that is, the cover nonwoven fabric 20 is positioned only in a portionwhere rigidity is high and wrinkles and folds are unlikely to occur,both the side portions of the cover nonwoven fabric 13 are unlikely tocontract in the front-back direction LD, and wrinkles are unlikely to beformed on the both side portions of the cover nonwoven fabric 13, andcollapse of the holes 14 is unlikely to occur. Further, even if the bothend portions in the width direction of the cover nonwoven fabric 13 donot cover a back surface side of the base portions of the side gathers60, and the gather nonwoven fabrics 62 cover the back surface side ofboth end portions in the width direction of the cover nonwoven fabric13, the liquid impervious sheet 11 can be concealed with the covernonwoven fabric 13 and the gather nonwoven fabric 62. In that case, whenthe total luminous transmittance of the gather nonwoven fabric 62 is 60to 90%, even in portions where the gather nonwoven fabrics 62 hide thecover nonwoven fabric 13, the holes 14 of the perforated nonwoven fabricare transparent and can be visually recognized sufficiently, and it canbe recognized that a portion having the air-permeability-improvingfunction extends to the side gathers 60. Consequently, the visual effectof the holes 14 is sufficiently exerted.

One preferred embodiment is that folded portions 13 r are included atboth the end portions in the width direction of the cover nonwovenfabric 13 in order to prevent wrinkles on both the side portions of thecover nonwoven fabric 13 and collapsing of the holes 14 as illustratedin FIG. 11. The folded width of the folded portion 13 r is preferably 5to 30 mm, particularly preferably 10 to 20 mm. In addition, even in thecase of providing the folded portions 13 r, it is preferable to providenon-fixed portions with respect to the inner member 200 at both the endportions in the width direction as described above. As a result, thestiffness of portions of the cover nonwoven fabric 13 is increased wherecontraction is likely to occur in the front-back direction LD, andwrinkling and collapse of the holes 14 are unlikely to occur. Whether ornot to join the back surfaces of the folded cover nonwoven fabric 13 isarbitrary, but if at least at the fold portions (each having the rangeof about 3 to 8 mm in width), the back surfaces of the cover nonwovenfabric are not bonded each other with a hot melt adhesive or the like,there is an advantage that the side edges are rounded such that thetexture is not rough. Further, since a nonwoven fabric is doubled in thefolded portions 13 r, when the liquid impervious sheet 11 and the gathernonwoven fabric 62 are fixed with a hot melt adhesive, even if a largeamount of adhesive is applied to an intermediate portion in the widthdirection, the adhesive does not ooze out. In this manner, the adhesivestrength of the end portions of the cover nonwoven fabric 13 in thewidth direction increases, and the flexibility can be further increasedat the intermediate portion in the width direction by reducing theadhesive material.

In the cover nonwoven fabric 13, as long as a region where the holes 14are formed extends from a portion overlapping with the front side outermember 12F to a portion overlapping with the back side outer member 12B,there may be a region without the holes 14 partly in the front-backdirection LD. However, it is desirable to provide the holes 14throughout totally in the front-back direction in consideration of theeffect of improving air permeability. On the other hand, in theembodiment in which both the end portions of the cover nonwoven fabric13 in the width direction WD have regions without the holes 14, wheneach hole 14 is opened by a method other than punching with a cutter, aswill be described later, fibers at the edge of the hole 14 are retractedoutside or in the vertical direction, and the edge portion of the hole14 bends-up, and the thickness of a perforated region becomes thickerthan that of a non-perforated region. Therefore, when a material of thecover nonwoven fabric 13 is stored in a rolled state, the non-perforatedregions are loosely wound, and wrinkles and folds may be formed in thenon-perforated regions at both the sides. Therefore, it is desirablethat the holes 14 be formed in the whole width direction WD as in theillustrated embodiment. By forming the holes in the cover nonwovenfabric 13 in the manufacturing process of a diaper, materials withoutholes can be used, and positions of the holes can be arbitrarilycontrolled. However, by introducing a device for forming the holes, thewhole of a manufacturing facility becomes large, and a burden of costand maintenance increases. In addition, it is difficult to adjust thehole shape and softness in a manufacturing line at high speed.Therefore, it is preferable to manufacture a diaper using a material inwhich the holes are formed throughout totally in the front-backdirection and the width direction.

A planar shape (opening shape) of each hole 14 can be appropriatelydetermined. It can have an arbitrary shape such as an elongated holeshape as illustrated in FIGS. 17(a) and 17(b), a perfect circle asillustrated in FIGS. 17(c) and 17(e), an ellipse as illustrated in FIG.17(d), a polygon such as a triangle, a rectangle, and a rhombus, a starshape, a cloud shape and the like. Although the dimensions of theindividual holes 14 are not particularly limited, but the dimension inthe front-back direction (maximum dimension in the front-back directionLD) 14L is preferably is 0.4 to 1.8 mm, particularly preferably 0.8 to1.3 mm, and the width direction dimension (the maximum dimension in thewidth direction WD) 14W is preferably 0.3 to 1.5 mm, particularlypreferably 0.5 to 1.0 mm. In the case where the shape of the hole 14 islong in one direction like a long hole shape, an elliptic shape, arectangular shape, and a diamond shape, the maximum dimension in thelongitudinal direction is preferably 2.5 times or less the maximumdimension in the direction orthogonal thereto. Further, when the shapeof the hole 14 is long in one direction, it is desirable that thelongitudinal direction of the hole 14 be the front-back direction LD,but it may be the width direction WD or the oblique direction.

An area and an area rate of the individual holes 14 may be appropriatelydetermined, but the area is preferably about 0.2 to 2.5 mm²(particularly about 0.5 to 1.5 mm²), and the area rate is about 0.5 to5.0% (particularly about 1.0 to 2.5%).

Although the planar arrangement of the holes 14 can be appropriatelydetermined, a regularly repeated plane arrangement is preferred. Inaddition to the regularly repeated plane arrangement, such as an obliquelattice shape as illustrated in FIG. 17(a), a hexagonal lattice shape(also referred to as a staggered shape) as illustrated in FIG. 17(b), asquare lattice shape as illustrated in FIG. 17(c), a rectangular latticeshape as illustrated in FIG. 17(d), and a parallel lattice shape asillustrated in FIG. 17(e) (as illustrated in the drawing, two groups ofmany parallel oblique direction rows are provided so as to cross eachother) (including those inclined at an angle of less than 90° withrespect to the front-back direction LD), a group of the holes 14 (thegroup may be regularly or irregularly arranged, and may be a pattern ora letter shape) can be regularly repeated.

An interval 14 y of the two adjacent holes in the front-back directionand an interval 14 x of the two adjacent holes in the width directioncan be appropriately determined, but in consideration of airpermeability, it is desirable to set each within the range of 0.5 to 8mm, particularly 1 to 5 mm, and the front-back direction interval 14 yand the width direction interval 14 x are preferably set to be withinthe range of 1 to 5 mm on average. In particular, as illustrated in FIG.17(d), when the shape of the hole 14 is elongated in the front-backdirection LD, a row of the holes 14, which are aligned in the front-backdirection LD at the intervals 14 y in the front-back direction narrowerthan the dimension 14L in the front-back direction of the hole 14, isrepeated at a predetermined interval in the width direction WD, and theinterval 14 x of the two adjacent holes in the width direction is widerthan the dimension 14L in the front-back direction of the hole 14 (morepreferably three times or more the dimension 14W in the width directionof the hole 14), it is preferable since softness and bulkiness are notimpaired while remarkably improving the air permeability, and also thereis no decrease in the tensile strength of the sheet in the front-backdirection which is important in manufacturing.

The first to third embodiments can be applied to the sectional shape ofthe hole 14. In the first embodiment, the thickness of a nonwoven fabricdecreases from a periphery of the hole 14 toward an edge of the hole 14,and the edge of the hole 14 is positioned in the middle in the thicknessdirection of the nonwoven fabric as illustrated in FIG. 14. In thesecond embodiment, an edge portion 14 e of the hole 14 is bent-up towarda front surface side, and the bending-up height 14 h is substantiallyuniform as illustrated in FIG. 15. In the third embodiment, the edgeportion 14 e of the hole 14 bends-up toward a front surface side, andthe edge portion 14 e includes a highest opposing portion having thehighest bending-up height 14 i; and a lowest opposing portion beingorthogonal in the opposing direction to the highest opposing portion andhaving the lowest bending-up height 14 j as illustrated in FIG. 16. Fromthe viewpoint of air permeability, the second and third embodiments inwhich a portion including the holes 14 is thicker than the surroundingsare desirable. In particular, the third embodiment is preferable since agap formed by a difference in bending-up heights 14 i and 14 j in theedge portion 14 e of the hole 14 contributes to improvement of airpermeability. In the second and third embodiments, it is preferable thatthe bending-up heights 14 g, 14 h, and 14 i (the apparent heightmeasured by using an optical microscope in a state where a pressure isnot applied) be about 0.2 to 1.2 mm, and the highest bending-up height14 i in the third embodiment is preferably about 1.1 to 1.4 times thelowest bending-up height 14 j.

The hole 14 may be a punched hole whose edge portion is formed by cutends of fibers and may be a non-punched hole (to have an edge portionwith fibers having a high density) having almost no cut end of the fiberat the edge portion of the hole 14 and formed by inserting and pushing apin among the fibers. The former is suited for the first embodiment, andthe latter is suited for the second and third embodiments. For example,when the hole 14 having a long dimension in one direction is formed byinserting a pin, the fibers in the edge portion 14 e of the hole 14 areretracted outside or in a vertical direction, the edge portion 14 e ofthe hole 14 bends-up, and the bending-up height i of the opposingportion in the longitudinal direction of the hole 14 is higher than thebending-up height j of the opposing portion being orthogonal in theopposing direction to the longitudinal direction. In the second andthird embodiments, the edge portion at a part where the edge portion 14e of the hole 14 is bent-up toward the surface may have a lower densityof the fibers than those of surroundings in some cases, but it ispreferable that it be equal to or higher than those of the surroundings.Further, it is desirable that the fibers at the edge portion of the hole14 be fusion bonded to each other, but may not be fused.

(Regarding Total Luminous Transmittance of Outer Member)

When the front side outer member 12F and the back side outer member 12Bhave, at least at portions overlapping with the cover nonwoven fabric 13and not having any elastic member, the total luminous transmittance of50% or more (preferably 65% or more), it is preferable since even inportions hidden by the front side outer member 12F and the back sideouter member 12B in the cover nonwoven fabric 13, the holes 14 of theperforated nonwoven fabric are transparent and can be visuallyrecognized sufficiently, and therefore, it can be recognized that aportion having an air-permeability-improving function is provided notonly a part between the front side outer member 12F and the back sideouter member 12B, but also on both the front and back sides of the part,and the visual effect of the holes 14 can be sufficiently exerted. Thetotal luminous transmittance of the outer members 12F and 12B ismeasured in a state where the outer sheet layer 12S and the inner sheetlayer 12H are overlapped.

(Regarding Decorative Printing)

Decorative printing 27 and 28 (inner decorative printing 28) such ascharacters and patterns can be provided on the liquid impervious sheet11 so as to be visible on an outer surface of a product. When such innerdecorative printing 28 is provided, if the inner decorative printing 28and the holes 14 of at least a part of the cover nonwoven fabric 13 arearranged to overlap with each other, it is preferable since the holes 14of a perforated nonwoven fabric emerge against a background of the innerdecorative printing 28, and the holes 14 can be easily seen through theouter surface. To prevent positional deviation of the inner decorativeprinting 28 during manufacturing, it is also possible to print aso-called registration mark 29 on the liquid impervious sheet 11.

On the other hand, since the inner decorative printing 28 is coveredwith the perforated nonwoven fabric, the appearance as decoration may bedeteriorated. Therefore, regarding the decoration emphasizing theappearance, it is desirable that an outer decorative sheet 25 havingouter decorative printing 27 be provided on an outer side of the covernonwoven fabric 13 at least in one of the region where the front sideouter member 12F and the cover nonwoven fabric 13 overlap each other andthe region where the back side outer member 12B and the cover nonwovenfabric 13 overlap each other. In this case, to make the holes 14 of theperforated nonwoven fabric transparent and possible to be visuallyrecognized sufficiently even in the portions hidden by the front sideouter member 12F and the back side outer member 12B in the covernonwoven fabric 13, both the edges on the crotch side of both the outerdecorative sheets 25 are preferably spaced apart by about 5 to 30 mmfrom an edge portion on the crotch side of the front side outer member12F and from an edge portion on the crotch side of the back side outermember 12B. Additionally, each of the outer decorative sheets preferablyhas a width being narrower than that of the cover nonwoven fabric 13such that both side edges of the outer decorative sheet 25 are spacedapart by about 5 to 30 mm from each of the both side edges of the covernonwoven fabric 13.

As in the illustrated embodiment, the liquid impervious sheet 11 mayhave, at a region overlapping with the outer decorative sheet 25, theinner decorative printing 28, but preferably does not have, at theregion, the inner decorative printing 28 (such that the outer decorativesheet 25 and the inner decorative printing 28 do not overlap). That isbecause even if a member with low visible light permeability is used forthe outer decorative sheet 25, it can be prevented that the innerdecorative printing 28 is partially hidden by the outer decorative sheet25, and the appearance does not deteriorate. Further, the outerdecorative sheet 25 may overlap with the registration mark 29. In thatcase, the outer decorative printing 27 and the registration mark 29 mayoverlap each other. However, it is preferable that a printing positionof the outer decorative printing 27 and a position of the registrationmark 29 are adjusted so as not to overlap, since the appearancedeterioration of the outer decorative printing 27 due to overlappingviewing of the outer decorative printing 27 and the registration mark 29can be prevented.

The type, shape, and size of the inner decorative printing 28 and theouter decorative printing 27 are not particularly limited. As thedecorative printing 27 and 28, in addition to continuous decorativeprinting (refer to the inner decorative printing 28 of FIGS. 2, 7, and8) composed of many elements such as characters (such as a size, a brandname, a manufacturer name, and a picture name) and pictures, which areregularly repeated in the front-back direction LD and the widthdirection WD, there is an intermittent decorative printing (refer to theouter decorative printing 27 of FIG. 2) arranged only on one or both ofthe front and back of a product, such as a product logo, a picture of acharacter, and a photograph. Either of the inner decorative printing 28and the outer decorative printing 27 may be adopted. However, it shouldbe noted as follows. The continuous decorative printing is a repetitionof a large number of elements, and there is almost no influence onappearance even as a background of the perforated nonwoven fabric. Onthe other hand, when the intermittent decorative printing is coveredwith the perforated nonwoven fabric, there is a difference in appearancebetween the portions having the holes 14 and the other portions, and theintermittent decorative printing is partly hidden due to high concealingproperty of the edge portions of the holes 14. Consequently, thedeterioration of appearance becomes remarkable. Therefore, it ispreferable to distinguish a member having the inner decorative printing28 and a member having the outer decorative printing 27, and apply thecontinuous decorative printing to the inner decorative printing 28 andthe intermittent decorative printing to the outer decorative printing27. Although the inner decorative printing 28 may be intermittentdecorative printing, it is desirable that the inner decorative printing28 does not have at least a complicated pattern.

The inner decorative printing 28 may be printed on either the frontsurface side or the back surface side of the liquid impervious sheet 11or may be printed on both the front and back surfaces. Similarly, theouter decorative printing 27 may be printed on either the front surfaceside or the back surface side of the outer decorative sheet 25 or may beprinted on both the front and back surfaces.

The base material of the outer decorative sheet 25 is not particularlylimited as long as it is suited for printing, and paper such as crepepaper, a resin film, or the like can be used, for example. When thecrepe paper is used, its thickness is preferably 100 to 150 μm, and thedensity is preferably 100 to 200 kg/m³. Crepe paper having suchthickness and density can be produced with a crepe ratio of around 10%at a basis weight of 10 g/m² or more. The density can be calculated fromthe basis weight and the thickness. Further, the crepe ratio is a valuecalculated by the equation; ((peripheral speed of Yankeedryer)−(peripheral speed of winding reel))/(peripheral speed of Yankeedryer)×100(%). When the outer decorative sheet 25 is provided near anouter surface of a product, it is easy to see from the outside of theproduct. Therefore, as illustrated in the figure, the outer decorativesheet 25 is desirably provided adjacent to the inner surface of theouter sheet layer 12S between the outer sheet layer 12S and the innersheet layer 12H, but it may be provided adjacent to an outer surface ofthe inner sheet layer 12H. Further, it may be provided between the outermember 12F, 12B and the inner member.

In the case of providing the indicator 80 which discolors in contactwith the liquid content of excrement, the indicator 80 is preferablyprovided on the liquid impervious sheet 11 at a region not having theinner decorative printing 28 so as to be separated by 5 mm, particularly10 mm or more, from the inner decorative printing 28. It is preferablethat at least a part of the indicator 80 when provided, particularly inthe case of a belts-shaped or streaks-like pattern extending in thefront-back direction LD, at least one belt or streak be disposed so asto overlap with the holes 14 of the cover nonwoven fabric 13 at aplurality of places. For example, preferably, in the case where aplurality of rows of the holes 14 are provided as in FIGS. 17(a), 17(b),17(c), and 17(d), at least one belt or streak in each of the strips-likeor streaks-like patterns of the indicator 80 overlaps with the row ofthe holes 14. In addition, as in the parallel grid illustrated in FIG.17(e), it is preferable that the strips and streaks of the indicator 80be always arranged so as to overlap with the holes even if the belts andstreaks are deviated somewhat due to camber of the material. As aresult, a user can easily notice discoloration of the indicator 80because of two kinds of visibility: not only by discoloration of theindicator 80 but also by the difference in color of the indicator 80looking through the holes 14 and the indicator 80 visible through thenonwoven fabric. At this time, when the width per one belt or streak ofthe indicator 80 is twice or more the dimension 14W in the widthdirection of the hole 14 of the cover nonwoven fabric 13 and is narrowerthan the width direction interval 14 x of the holes 14, the indicator 80and the holes 14 are likely to overlap even if the positions areslightly deviated, and also it is preferable because the visibility ofthe indicator 80 in an overlapped state is remarkably improved.Incidentally, if the total luminous transmittance of the cover nonwovenfabric 13 (at a portion without the holes 14) is 60 to 90%, it ispreferable since the difference between the color visible through theholes 14 and the color visible through the nonwoven fabric is increased,and the holes 14 are easily noticed.

(Inner and Outer Joined Portion)

The inner member 200 can be fixed to the outer members 12F and 12B by ajoining means by material welding such as heat seal and ultrasonic sealand a hot melt adhesive. In the illustrated embodiment, the inner member200 is fixed to the inner surfaces of the outer members 12F and 12B witha hot melt adhesive applied on a back surface of the inner member 200,that is, in this case, a back surface of the liquid impervious sheet 11,and the root portion 65 of the side gather 60. The inner and outerjoined portions 201 for fixing the inner member 200 and the outermembers 12F and 12B can be provided to almost entirely in the regionwhere both are overlapped with each other, and for example, the innerand outer joined portion 201 can be provided in a portion excluding bothend portions of the inner member 200 in the width direction.

As illustrated in FIGS. 9 and 10, one preferred embodiment is that atleast either of the front side outer member 12F and the back side outermember 12B is joined to the inner member 200 at regions overlapping withboth the end portions in the width direction of the inner member 200,and is not joined or is intermittently and peelably joined to the innermember 200 at a part on a crotch side or a whole part in the front-backdirection LD of a region between the regions overlapping with the bothend portions in the width direction of the inner member 200. In thiscase, a gap between the inner member 200 and at least one of the frontside outer member 12F and the back side outer member 12B communicateswith the crotch side to improve air permeability. In addition, since thecover nonwoven fabric 13 (perforated nonwoven fabric) hidden by at leastone of the front side outer member 12F and the back side outer member12B can be directly seen by pulling up this part, the high visual effectof the holes 14 can be obtained.

Explanation of Terms Used Herein

The following terms in the specification have the following meaningsunless otherwise specified in the specification.

“Front-back (longitudinal) direction” means a direction connecting theventral side (front side) and the dorsal side (back side). “Widthdirection” means a direction orthogonal to the front-back direction(right-left direction).

“Front surface side” means a side closer to the skin of a wearer wearingan underpants-type disposable diaper, and “back surface side” means aside far from the skin of a wearer wearing an underpants-type disposablediaper.

“Front surface” means a surface of a member closer to the skin of awearer wearing an underpants-type disposable diaper, and “back surface”means a surface far from the skin of a wearer wearing an underpants-typedisposable diaper.

“Total luminous transmittance” means a value measured according to JIS-K7105 for total luminous transmittance.

“Area rate” means a rate of a target portion to a unit area and isexpressed as a percentage obtained by dividing a total area of targetportions (for example, the holes) in a target region (for example, acover nonwoven fabric) by an area of the target region. In a mode inwhich a large number of the target portions are provided at intervals,it is desirable to set the size of the target region such that ten ormore target portions are included therein and obtain the area rate. Forexample, the area rate of the holes can be measured by the followingprocedure, for example, using the trade name VHX-1000 manufactured byKEYENCE CORPORATION under a measurement condition of magnification of×20.

(1) Set a lens with a magnification of ×20 and adjust a focus. Adjustthe position of a nonwoven fabric such that 4 holes×6 holes come insight.

(2) Specify the brightness of “hole” and measure the area of the hole.

(3) Click extraction color of [Area Measurements] in[Measurement/Comment]. Click “hole”.

(4) Click [Block Measurement], check [Displaying the measurement resultwindow] and save the measurement result as CSV data.

“Stretch rate” means the value relative to the natural length (100%).

“Gel strength” is measured as follows: A super absorbent polymer of 1.0g is added to artificial urine of 49.0 g (mixture of urea: 2 wt %,sodium chloride: 0.8 wt %, calcium chloride dihydrate: 0.03 wt %,magnesium sulfate heptahydrate: 0.08 wt %, and ion exchanged water:97.09 wt %) and the mixture is stirred with a stirrer. After leavinggenerated gel for three hours in a thermo hygrostat bath at 40° C.×60%RH, the gel is cooled to room temperature, and the gel strength of thegel is measured with Curdmeter (MAX ME-500, manufactured by I. TechnoEngineering Co., Ltd).

“Basis weight” is measured as follows. After the sample or test piece ispreliminarily dried, it is allowed to stand in a test chamber orequipment under the normal conditions (the test location is at atemperature of 20±5° C. and with a relative humidity of 65% or less)until the constant mass. The preliminary drying is to make the sample ortest piece be constant mass in an environment not exceeding atemperature of 50° C. and a relative humidity of 10 to 25%. For fiberswith an official moisture regain of 0.0%, preliminary drying may not beperformed. A sample of dimensions of 200 mm×250 mm (±2 mm) is cut usinga cutting template (200 mm×250 mm, ±2 mm) from the test piece in theconstant mass. The basis weight is set by weighing the sample,multiplying by 20, and calculating the weight per one square meter.

“Thickness” is automatically measured under the conditions of a load of10 gf/cm² and a pressing area of 2 cm² using an automatic thicknessmeasuring device (KES-G5 handy compression measurement program).

“Water absorption capacity” is measured according to JIS K7223-1996“Testing method for water absorption capacity of super absorbentpolymers”.

“Water absorption rate” is the “time that elapses before the end point”when JIS K7224-1996 “Testing method for water absorption rate of superabsorbent polymers” has been carried out using 2 g of superabsorbentpolymers and 50 g of physiological saline solution.

“Spread state” means a flatly spread state without contraction or slack.

The dimension of each part means the dimension in the spread state, notthe natural length state, unless otherwise stated.

When environmental conditions in tests and measurements are notdescribed, the tests and measurements shall be carried out in a testroom or apparatus under normal conditions (the test location is at atemperature of 20±5° C. and with a relative humidity of 65% or less).

INDUSTRIAL APPLICABILITY

The present invention is applicable to an underpants-type disposablediaper.

REFERENCE SIGNS LIST

-   -   11 liquid impervious sheet    -   12A side seal portion    -   12B back side outer member    -   12F front side outer member    -   12H inner sheet layer    -   12S outer sheet layer    -   13 cover nonwoven fabric    -   14 hole    -   18 idle elastic member    -   200 inner member    -   201 inner and outer joined portion    -   25 outer decorative sheet    -   27, 28 decorative printing    -   27 outer decorative printing    -   28 inner decorative printing    -   29 registration mark    -   30 top sheet    -   40 intermediate sheet    -   50 absorbent element    -   56 absorber    -   58 wrapping sheet    -   60 side gather    -   62 gather nonwoven fabric    -   80 indicator    -   A1 non-stretchable region    -   A2 stretchable region    -   C gluteal cover portion    -   L intermediate region    -   LD front-back direction    -   LO leg opening    -   T lower torso region    -   U under-waist portion    -   W waist portion    -   WD width direction    -   WO waist opening

1. An underpants-type disposable diaper, in which a front side outermember disposed in a front body and a back side outer member disposed ina back body are separately provided, the front side outer member and theback side outer member are spaced apart in the front-back direction atthe middle in the front-back direction, an inner member having a liquidpervious top sheet, a liquid impervious sheet, and an absorberinterposed therebetween extends in the front-back direction from thefront side outer member to the back side outer member, the inner memberis joined to each of the front side outer member and the back side outermember, a cover nonwoven fabric covering a back surface of the innermember is provided from between the front side outer member and theinner member to between the back side outer member and the inner member,both sides of the front side outer member and both sides of the backside outer member are joined to each other, a waist opening and a pairof right and left leg openings are included, and elastic members areincorporated in the front side outer member and the back side outermember, wherein the cover nonwoven fabric is provided with a pluralityof holes penetrating a front surface and a back surface of the covernonwoven fabric from between the front side outer member and the innermember to between the back side outer member and the inner member atintervals, and the front side outer member and the back side outermember have, at least at portions overlapping with the cover nonwovenfabric and not having any elastic member, a total luminous transmittanceof 50% or more.
 2. The underpants-type disposable diaper according toclaim 1, comprising inner decorative printing, which is visible on outersurfaces of the front side outer member and the back side outer member,on the liquid impervious sheet at least in a region thereof, whichoverlaps the front side outer member and the back side outer member,wherein the inner decorative printing overlaps with the holes at leastin a part of the cover nonwoven fabric.
 3. The underpants-typedisposable diaper according to claim 2, wherein at least either of aregion where the front side outer member and the cover nonwoven fabricoverlap with each other and a region where the back side outer memberand the cover nonwoven fabric overlap with each other includes, on anouter side of the cover nonwoven fabric, a portion provided with anouter decorative sheet having outer decorative printing and a portionnot having the outer decorative sheet.
 4. The underpants-type disposablediaper according to claim 3, wherein the inner decorative printing is acontinuous decorative printing comprising a plurality of elementsregularly repeating in the front-back direction and the width direction,and the outer decorative printing is an intermittent decorative printingarranged only in one or both of front and back sides of a product. 5.The underpants-type disposable diaper according to claim 1, wherein atleast either of the front side outer member and the back side outermember is joined to the inner member, at regions overlapping with bothend portions in the width direction of the inner member, and is notjoined or is intermittently and peelably joined to the inner member, ata part on a crotch side or a whole part in the front-back direction of aregion between the regions overlapping with the both end portions in thewidth direction of the inner member.
 6. The underpants-type disposablediaper according to claim 1, comprising side gathers extending from bothsides of the inner member so as to be in contact with the legs of awearer and each of the side gathers having a base end on a side portionon a back surface side of the liquid impervious sheet in the innermember, and a gather nonwoven fabric forming an outer surface at leastfrom the base end to a tip end, wherein the cover nonwoven fabricextends at least from between a base portion of one of the side gathersand the liquid impervious sheet to between a base portion of the otherside gather and the liquid imperious sheet, and the gather nonwovenfabric has a total luminous transmittance of 60 to 90%.
 7. Theunderpants-type disposable diaper according to claim 2, wherein at leasteither of the front side outer member and the back side outer member isjoined to the inner member, at regions overlapping with both endportions in the width direction of the inner member, and is not joinedor is intermittently and peelably joined to the inner member, at a parton a crotch side or a whole part in the front-back direction of a regionbetween the regions overlapping with the both end portions in the widthdirection of the inner member.
 8. The underpants-type disposable diaperaccording to claim 3, wherein at least either of the front side outermember and the back side outer member is joined to the inner member, atregions overlapping with both end portions in the width direction of theinner member, and is not joined or is intermittently and peelably joinedto the inner member, at a part on a crotch side or a whole part in thefront-back direction of a region between the regions overlapping withthe both end portions in the width direction of the inner member.
 9. Theunderpants-type disposable diaper according to claim 4, wherein at leasteither of the front side outer member and the back side outer member isjoined to the inner member, at regions overlapping with both endportions in the width direction of the inner member, and is not joinedor is intermittently and peelably joined to the inner member, at a parton a crotch side or a whole part in the front-back direction of a regionbetween the regions overlapping with the both end portions in the widthdirection of the inner member.
 10. The underpants-type disposable diaperaccording to claim 2, comprising side gathers extending from both sidesof the inner member so as to be in contact with the legs of a wearer andeach of the side gathers having a base end on a side portion on a backsurface side of the liquid impervious sheet in the inner member, and agather nonwoven fabric forming an outer surface at least from the baseend to a tip end, wherein the cover nonwoven fabric extends at leastfrom between a base portion of one of the side gathers and the liquidimpervious sheet to between a base portion of the other side gather andthe liquid imperious sheet, and the gather nonwoven fabric has a totalluminous transmittance of 60 to 90%.
 11. The underpants-type disposablediaper according to claim 3, comprising side gathers extending from bothsides of the inner member so as to be in contact with the legs of awearer and each of the side gathers having a base end on a side portionon a back surface side of the liquid impervious sheet in the innermember, and a gather nonwoven fabric forming an outer surface at leastfrom the base end to a tip end, wherein the cover nonwoven fabricextends at least from between a base portion of one of the side gathersand the liquid impervious sheet to between a base portion of the otherside gather and the liquid imperious sheet, and the gather nonwovenfabric has a total luminous transmittance of 60 to 90%.
 12. Theunderpants-type disposable diaper according to claim 4, comprising sidegathers extending from both sides of the inner member so as to be incontact with the legs of a wearer and each of the side gathers having abase end on a side portion on a back surface side of the liquidimpervious sheet in the inner member, and a gather nonwoven fabricforming an outer surface at least from the base end to a tip end,wherein the cover nonwoven fabric extends at least from between a baseportion of one of the side gathers and the liquid impervious sheet tobetween a base portion of the other side gather and the liquid imperioussheet, and the gather nonwoven fabric has a total luminous transmittanceof 60 to 90%.
 13. The underpants-type disposable diaper according toclaim 5, comprising side gathers extending from both sides of the innermember so as to be in contact with the legs of a wearer and each of theside gathers having a base end on a side portion on a back surface sideof the liquid impervious sheet in the inner member, and a gathernonwoven fabric forming an outer surface at least from the base end to atip end, wherein the cover nonwoven fabric extends at least from betweena base portion of one of the side gathers and the liquid impervioussheet to between a base portion of the other side gather and the liquidimperious sheet, and the gather nonwoven fabric has a total luminoustransmittance of 60 to 90%.